A conventional bicycle chain is shown in FIGS. 9 and 10, and generally includes multiple connection units “A” each composed of two inner link plates “A1”, two first pins “A2” and two second pins “A3” connected between the two inner link plates “A1”. The multiple connection units “A” are connected to each other and two outer link plates “B” are connected to two adjacent ends of the two connection units “A” by the second pins “A3” so as to from the bicycle chain. Each of the second pins “A3” has a fixing end “A31” and a connection end “A32” on two respective ends thereof. The connection end “A32” is connected with a neck “A33”. The two outer link plates “B” each have a through hole “B1” and an engaging hole “B2”, wherein the fixing end “A31” is engaged with the through hole “B1”. The engaging hole “B2” includes a first hole “B21” and a second hole “B22”, wherein the inner diameter of the first hole “B21” is larger than that of the second hole “B22” and communicates with the second hole “B22”. The connection end “A32” is engaged with the first hole “B21”. The second hole “B22” is smaller than that of the connection end “A32”. The second hole “B22” is wider than that of the neck “A33”. A rib “B23” is located within the second hole “B22” and each of the two outer link plates “B” includes two curved sides on opposite sides thereof.
It is noted that there is a gap “F” of 2.36 mm formed between the adjacent inner link plates “A1” so that a gap “D” is formed between the inner link plate “A1” and the adjacent outer link plate “B”. The gap “D” makes relative movement between the second pins “A3” and the outer link plates “B”. When the derailleur system changes gears, a force will pull the second pins “A3” which moves toward the through hole “B1” and generates noise or even drop from the chain.
The present invention intends to provide a bicycle chain and only a very small gap is formed between the inner link plates so that the chain does not generate noise during changing gears.